Properties of a Soluble Lead Flow Battery Recycled with Hydrogen Peroxide

The service life of soluble lead flow batteries can be extended by periodic addition of H2O2, especially when it failed. However in first few cycles after H2O2 treatment, its coulombic efficiency is very low. To clarify it, the properties of electrode and electrolyte, and cycle performance have been systematically analyzed. It has been found that the negative/positive electrode reactions have serious overpotentials during early charging due to oxygen, which are produced and dissolved into the electrolyte during H2O2 treatment. With increasing the cycle number, the polarization degree decreases to the normal level of the battery. To solve it, oxygen is removed using argon after H2O2 treatment. The flow cell is normally recovered in the cycling performance. The average coulomb efficiency is 94.5 +/- 5.8 % for 500 times. After H2O2 treatment and oxygen removal, it exhibits a good cycling performance at the average coulomb efficiency of 93.9 +/- 4.2 % for another 500 times. In this work, the remediation of H2O2 have been applied to remove positive and negative residuals after the failure of cells. However the formation of oxygen brings about a significant overpotential during this procedure, lowering the efficiency of battery in the initial cycles. Argon is introduced to remove oxygen for 1 hour. The cell exhibits the good cycling perfromances as before. The lifespan of SLFB can be extended by the treatments of H2O2 and oxygen removal.image